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Hi! I feel transistors used in cable TV industry are more suited , cheap and universaly available. I would recommend BFR96, BFR91, MPS571, 2SC3359 (7Ghz) and 2SC2570A (5Ghz) devices. The later is

I use 2SC1815 for my BITX, which i could get for $2/100pc. My first built was using 2SC945 salvaged from IC-R71 receiver, both are multipurpose NPN, easy to obtain. 2N3904 specs is higher from

Rob It will be interesting to see what specific microwave transistors you recommend for the BITX design. Hopefully, they will be generally available and at a relatively low cost. Since the BITX

Julius If your signal generator puts out enough signal to light an LED then you can easily use it and a capacitor to 'measure' inductance. Just put an LED in series with your inductor and a

there is smilar coils available here almost similar in shape, 10mm canned coils no capacitor, but it is use for TV spare parts, so i bought a few, and try to take a look inside, the primary wound is

Hi All, I have been doing some Spice simulations, and after playing around with it a bit, it is evident that using microwave transistors will improve things a lot over the HF general purpose

Hi! Here in VU I noticed two type of FM 10.7Mhz IF transformers. One is resonant using an external 82Pf giving the inductance of abt 2.69uH. Other one is resonant using internal 68pf that results

Hi! Chris, The first BITX I made was as per my PCB layouts the ver2. You can see the pic under photo section. This rig was also presented by me at IIT Indian Institute of Technology during their

Julius I got my 10.7 MHz IF transformers from an old/dead AM/FM receiver. If you do this, be sure that you do not try to use the discriminator transformer. It has different characteristics from the

Hi Rahul, can you give some more information about the 'significant improvement'? More output? More sensitive? Better balancing? Only one mixer changed to double balanced or both mixers/ Thanks in

Hi Rob, Nice to see people making use of the layout. The changes on the boards are: 1) BEC configration on Q1 Rf preamp to enable direct placement of high Ft devices like 2SC2570A or BFR91. 2)

Hi Rahul, I didn't look at the version 3 PCB carefully enough I guess. The notes sheet didn't seem to indicate that the mixer had changed. I'm actually using your version 3 board, but my IF is 6

Hi! I have used a doubly balanced config in one of the prototypes. Ver3 uploaded under FILES uses DBM. There is significant improvement in performance. The PCB also incorporates many other

Hi all, i have uploaded my BITX40 photos to the photo dir BITX40_JW, just to share to everyone. I have not yet complete the BPF to work on 40m, but directly connecting the RF amp input to the

Apparetnly f6feo using double balanced in his modification, and fahran in one earlier version pictured dbm but it is not implmented on schematic.

Hi, I just noticed that the first mixer, though it has four diodes in a ring configuration is only singly balanced. Has anyone tried putting a doubly balanced one in its place? It would give

QSL.net is notoriously slow, so I am also hosting Frank K0IYE's book on my website at: http://www.hanssummers.com/radio/k0iye/index.htm . I was not aware of the Spanish translation and I will add a

Today I am working with the BITX main transceiver board to put into perfect operation becoming my future multiband, multimode BITX. I have changed the VCO oscillator transistor for a BF494 and I

Hi! Thanks for suggestions. Will pass it on. 73 Rahul VU3WJM Rob Frohne <frohro@...> wrote: Hi Rahul, Thanks for sharing your friend's DDS. I looked at it, and have one suggestion. If

Hallo folks, I'm just going to use an AD9951 DDS made by a friend of mine: I0CG, Giuliano ( http://it.geocities.com/giulianoi0cg/ad9951.html ) ; his works is really fine (a very clean spectrum ) and